/*
 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/client/RequestDirector.java $
 * $Revision: 676020 $
 * $Date: 2008-07-11 09:38:49 -0700 (Fri, 11 Jul 2008) $
 *
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.client;

import java.io.IOException;

import org.apache.http.HttpException;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.protocol.HttpContext;

/**
 * A client-side request director. The director decides which steps are
 * necessary to execute a request. It establishes connections and optionally
 * processes redirects and authentication challenges. The director may therefore
 * generate and send a sequence of requests in order to execute one initial
 * request.
 * 
 * <br/>
 * <b>Note:</b> It is most likely that implementations of this interface will
 * allocate connections, and return responses that depend on those connections
 * for reading the response entity. Such connections MUST be released, but that
 * is out of the scope of a request director.
 * 
 * @author <a href="mailto:rolandw at apache.org">Roland Weber</a>
 * 
 * 
 *         <!-- empty lines to avoid svn diff problems -->
 * @version $Revision: 676020 $
 * 
 * @since 4.0
 */
public interface RequestDirector {

    /**
     * Executes a request. <br/>
     * <b>Note:</b> For the time being, a new director is instantiated for each
     * request. This is the same behavior as for <code>HttpMethodDirector</code>
     * in HttpClient 3.
     * 
     * @param target
     *            the target host for the request. Implementations may accept
     *            <code>null</code> if they can still determine a route, for
     *            example to a default target or by inspecting the request.
     * @param request
     *            the request to execute
     * @param context
     *            the context for executing the request
     * 
     * @return the final response to the request. This is never an intermediate
     *         response with status code 1xx.
     * 
     * @throws HttpException
     *             in case of a problem
     * @throws IOException
     *             in case of an IO problem or if the connection was aborted
     */
    HttpResponse execute(HttpHost target, HttpRequest request,
            HttpContext context) throws HttpException, IOException;

} // class ClientRequestDirector
